[Gmecm] Re: Fuel Economy

[Darrell]

Cowen: (and all)

Well, you are right, second times the charm.  Thank you for 
responding anyway, and getting a little action going on the thread.  
A lot of this information will be useful, thanks to all who posted on 
the topic.  Some of it went way over my head, but I'm here to learn.

Interesting idea about using a WBO2 sensor, has anyone actually tried 
this?  I mean replacing a stock NB with a WB on a stock computer?  
That in combination with changing the voltage threshold may allow you 
to set the AFR to a slightly leaner mixture overall.

I was thinking more of optimizing the ignition advance, perhaps 
advancing the timing a bit on light throttle acceleration, tweaking 
the deceleration enleanment up a bit, that sort of thing.

Definitely the low restriction exhaust system will help, I used to 
drive a Camaro with cheap turbo mufflers, when the mufflers blew out 
my gas mileage went up by 10%!   Also thinking about 1.6:1 rockers 
for the exhaust valves to increase the flow a little.

Not sure what I can do on the intake side, haven't really researched 
what's available for that engine, but I suspect not much.  Perhaps 
some 3.1l parts, I've heard that 3.1l heads make a fairly big 
difference.  A straighter intake tube with smooth sides rather than 
the ribbed stock hose may help as well, and perhaps a larger diameter 
MAF.  I'd actually like to get rid of the MAF altogether.

I tend to agree with Bruce's observation, if you make more power, you 
need to get into the throttle less for the same effect, and fuel 
economy is tied to engine RPM and throttle position...  That is, if 
you can resist the temptation to put your foot in it.

On 15 Sep 2005 at 16:33, Cowen wrote:

> Wow!  A bit of vigorous action on this topic!  This IS
> my first rodeo, at least in this arena, and normally I
> might not have responded to Darrell, but it seemed no
> one else was, so I gave it a whirl.  I thought I put
> in enough "maybes" to draw out some clarification from
> the experts...  Well! I have been severely chastised
> for some poor writing skills!
> 
> GAS said:
> > NB more sensitive at what ratio?  On what WB sites
> > are you referring
> > to?  
> 
> Not "NB more sensitive" at some other ratio, I
> understand NB to be very limited.  I meant to suggest
> that WB might allow closed loop with leaner AF ratios
> than stoich, which would be a probable benefit because
> although stoich is chemically the best ratio, "best"
> ratios vary depending on your needs, for power,
> emmissions, economy, driveability, etc...(hence PE
> mode).
> 
> What sites?  I have to admit, I've only skimmed some
> of the WB sites found in a Google search, I don't have
> any suggestions for which is most detailed...  But
> don't worry, none of them I saw are trying to use NB
> sensors outside stoich!
> 
> Gas also said:
> >The NB sensor is a switch centering around, and
> > being most
> > sensitive at stoich.  It's sensitivity deteriorates
> > the farther from stoich
> > (either direction) the AFR.  There are NB O2 sensor
> > voltage to AFR
> > curve charts on the net, that verify this.  By
> > design, NB sensors need
> > not be accurate at AFRs away from stoichiometric.
> 
> Thanks for clarifying and expanding on exactly what
> I'd said about NB O2 sensors!
> 
> GAS continued:
> >  There is WB O2
> > sensor technology
> > however, that allows for PCM closed loop operation
> > at ratios leaner
> > (or richer) than stoich.
> > 
> > GAS
> 
> Again, my case stated more eloquently. Now I know why
> no one else responded to Darrell! :)
>  
> 
> 
> **********************END TRANSMISSION**********************
> 
> 
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